I recently traveled with my husband and in-laws on a Scenic Ruby cruise from Budapest to Amsterdam just this past June and the trip exceeded our entire group's expectations. Some of the reviews posted below are absolutely ridiculous, as it seems that some people expect that the company can somehow control the weather as well as river water levels. Everything about our trip was excellent - the website makes it clear that if you have mobility issues, they'll do their best to accommodate you - and they definitely do. Yes, the gangways are narrow, but it's a small cruise ship with limited space, what do you expect? There is even a small elevator on board for passengers requiring wheelchairs.
The food is excellent and there are always plenty of options for vegetarians, the excursions are well thought-out and the staff are amazing, particularly our butler Tamas, room manager Gerry, and the bar staff (Irina, Marko and Victor) - the cruise director Adrian was incredibly helpful and did his absolute best to make sure everyone was happy and everything ran smoothly. I was really impressed by the amount of storage space in the rooms, and the design of the balconies were fantastic.
Some have noted that there is no fitness center on board - given that the Main is incredibly narrow, there is really no room for a fitness center as on some of the slightly larger Scenic ships. Also, I got plenty of exercise walking around all the cities we visited. Overall, I would absolutely recommend this cruise without hesitation.